Surgical clamping mechanism

ABSTRACT

A surgical instrument which has a frame, an elongated shaft, an end effector with first and second jaws for clamping tissue, a post cooperatively engaged with the proximal end of the second jaw received in a slot on the sidewall of a channel included as part of the first jaw, a pusher member affixed to the proximal end of the second jaw, and an actuator to effect movement of the pusher member from a forward position to a rearward position, is disclosed. When the pusher member moves rearwardly, the post rides in the slot in the sidewall and the second jaw moves from a closed position where it is adjacent the first jaw for clamping tissue to an open position for placing tissue between the jaws. The combination of cooperating elements of the instrument provides a convenient and simple mechanism for clamping or grasping tissue between the jaws. This mechanism decreases the force necessary to clamp the tissue and utilizes more of the effective length of the second jaw. These benefits in turn make it easier for the user of the instrument to clamp tissue and reduces the tendency of the second jaw to flex or twist during clamping, therefore providing the user with even greater control over the surgical procedure. Overall, the clamping or grasping mechanism incorporated into the surgical instrument provides an attractive alternative to the conventional prior art mechanisms for accomplishing these functions.

BACKGROUND OF THE INVENTION

This invention relates to instruments for performing surgicalprocedures. More particularly, it relates to the clamping mechanism ofthese instruments which enables the surgeon to clamp or grasp bodilytissue especially during endoscopic surgical procedures.

During an endoscopic surgical procedure, access to the surgical sitewithin the body cavity is provided through openings of a small diametermade in the body wall. An instrument frequently used to provide thisaccess is the trocar. The trocar is an assembly which includes anobturator and a cannula. The obturator has a sharp tip which is used topuncture the body wall to provide the access opening. The obturatorslides within the cannula, which is a hollow, cylindrical sleeve. Whenthe obturator has punctured the body wall, the obturator is removed fromthe cannula. The cannula, however, remains in place within the openingmade in the body wall by the obturator. Consequently, the cannulaprovides a cylindrical passageway to gain access to the surgical sitewithin the body cavity.

Accordingly, a characteristic feature of many endoscopic surgicalinstruments is a long cylindrical shaft which can slide through thetrocar cannula. At the business end of the shaft, which is the end ofthe instrument coming into contact with tissue at the surgical sitewithin the body cavity, an "end effector" is provided to manipulate thetissue in some way to carry out a desired surgical procedure. Thebusiness end, including the end effector, must likewise be capable ofsliding through the trocar cannula. At the opposite end of the shaft,there is an actuator operatively connected to the business end toremotely control the performance of the end effector. The actuator isconveniently housed in a frame which may include a pistol grip handlewith one or more pivoting triggers. Alternatively, the actuator mayinclude a lever, or the combination of a pivoting trigger and a lever.The actuator is activated when the surgeon pivots the trigger ordepresses the lever. These actions in turn cause the end effector toperform its desired function.

One particularly desired function of an end effector of an endoscopicsurgical instrument is the ability of the end effector to clamp or grasptissue. It may be necessary to gasp tissue so that it may be retractedor otherwise precisely positioned to carry out a particular procedure.Instruments which carry out these functions are conveniently referred toas graspers and retractors. In some procedures, it is desirable to clamptissue so that the clamped tissue may be fastened when staples are firedinto and through the tissue. Instruments with end effectors which firestaples into clamped tissue are referred to as linear staplers andcutters (cutters are so named because they simultaneously cut the tissuewith a knife between rows of fired staples).

The end effector of an endoscopic surgical instrument which can clamp orgrasp tissue typically has two opposed, elongated jaws. The jaws haveinternal tissue-contacting surfaces between which the tissue is clampedor gasped. The jaws are often described as a lower jaw and an upper jaw.The lower and upper jaws move relative to each other. When the jaws aremoved to an open position, the tissue clamping surfaces of the jaws arespaced from each other so that tissue can be placed between the twosurfaces. When the jaws are moved to their closed position, thetissue-contacting surfaces of the jaws are positioned adjacent eachother so that tissue placed between the jaws is clamped or grasped.Often, the tissue-contacting surfaces of graspers may be serrated toprovide an enhanced surface for grasping tissue, and both jaws pivotbetween their opened and closed positions. Linear cutters and staplershave conventionally had a fixed lower jaw and a pivoting upper jaw whichpivots from open to closed positions relative to the lower jaw. Thefixed lower jaw may include a channel for receiving a staple cartridge.The upper jaw typically includes an anvil. Accordingly, when a linearstapler or cutter is used, tissue is placed between the cartridge andanvil when the upper jaw is in the open position, the upper jaw ispivoted to its closed position to clamp tissue between the cartridge andanvil, and staples are subsequently fired from the cartridge into theclamped tissue for formation against the anvil.

A key feature of the clamping and grasping mechanisms of endoscopicsurgical instruments is the mechanism which causes the upper or lowerjaw to move from an open position for placing tissue between the jaws toa closed position for clamping that tissue. A common mechanism,particularly for endoscopic linear cutters, involves the use of a"camming" closure tube. This tube reciprocates back and forth. In itsrearward position, the jaws are in the open position. In its forwardmost position, the upper jaw has pivoted to its closed position so thatthe anvil and cartridge are adjacent each other. In its rearwardposition, the distal end of the tube is positioned proximally of theupper jaw (in other words, the tube sits behind the jaw). The upper jaw,which is more frequently referred to simply as the anvil, has what isreferred to as an outer, ramped camming surface at its proximal end.When the tube reciprocates from its rearward to forward position, thedistal end of the tube slides along, or "cams" against the outer cammingsurface of the anvil. This camming action causes the anvil to pivot fromits open to closed position.

Unfortunately, the camming mechanism for causing opposed jaws to clampor grasp tissue placed between them is undesirably inefficient. Thereare high frictional losses associated with the camming action as thedistal end of the tube slides against the ramped camming surface of theanvil. These high frictional losses create poor efficiency for themechanism. When the mechanism is inefficient, higher forces arenecessary to actuate the clamping mechanism. In other words, the surgeonusing the instrument will need to exert more pressure when he squeezesthe trigger or depresses the lever to actuate the clamping mechanism sothat the jaws close. Obviously, precise positioning of the end effectoris hampered and frustration mounts as the amount of pressure which thesurgeon must apply to damp increases.

Another difficulty with the use of the closure tube for camming is therequirement for the ramped camming surface on the anvil. This surface isreally "wasted" surface area on the anvil because that portion of theanvil where this surface is positioned may not be used to form staples.The staple-forming surface of the anvil, which is the internaltissue-contacting surface, has pockets or depressions embedded in itwhere staples fired from the cartridge are formed. The inner surface ofthe portion of the anvil which is opposite the outer, ramped cammingsurface cannot, by its nature contain the pockets or depressions forstaple formation. Therefore, staples are not formed along the entirelength of the inner surface of the anvil. This means that the anvil islonger than it needs to be. Consequently, when tissue is clamped betweenthe jaws, the jaws may undesirably "flex" or twist. This can frequentlybe a problem when thicker tissue is clamped between the jaws, becausethe force necessary to clamp thicker tissue is greater than the forcenecessary to clamp thinner tissue. When flexing or twisting of the jawsoccurs, it may cause the staples to malformed when they are fired,resulting in improperly fastened tissue.

Another problem with the ramped camming surface is that because itnecessitates the use of an anvil which is longer than thetissue-contacting surface of the cartridge, it becomes necessary toincorporate a "tissue stop" onto the anvil. The tissue stop retards thepassage of the tissue placed between the jaws into that portion of theanvil opposite the ramped camming surface where staples cannot be fired.The tissue stop is typically a pair of lateral surfaces descending fromthe elongated anvil body. These lateral surfaces come into contact withthe tissue when the tissue is placed between the jaws, and thereforeimpede further proximal movement of the tissue. Unfortunately, thetissue stop is sometimes ineffective to prevent rearward passage oftissue, and this, of course, can result in improperly fastened tissue.

Another difficulty observed in connection with the cam closure mechanismis that the opening between the jaws when the jaws are in the openposition, or "gap", created when the anvil has a ramped camming surfaceis less than what is desired. The greater the gap, the better. This isbecause a wider gap enables the surgeon to more easily position thetissue between the jaws before clamping. Proper tissue positioningincreases the likelihood of proper staple formation. In addition, afterstaples are fired, the jaws are returned to the open position, and oftenit is necessary to remove the spent staple cartridge and reload it witha new one for a subsequent firing. Once again, a greater gap makes iteasier for the surgeon or operating room assistant to remove a spentcartridge and reload it with a new one.

Finally, the cam closure mechanism suffers from a further deficiency. Ifa downward force is applied to the distal end of the anvil when the endeffector is positioned at the surgical site within the body cavity, theanvil will pivot from its open to closed position. This frequentlyoccurs when the anvil brushes up against bodily tissue or organs. Thisinadvertent closure can cause disruption and loss of time during asurgical procedure. Furthermore, because the anvil does not have a"positive" opening position, or securely fixed open position, the endeffector is incapable of acting as a forceps or graspers. This limitsthe flexibility and desirability of the instrument as a whole.

Another clamping mechanism is described in Russian Patent No. 728,848.This mechanism also has a reciprocating closure tube which moves fromrearward to forward positions for pivoting an anvil from an open toclosed position. Lateral pins are attached to the anvil, and the closuretube rides on these pins within slots on the closure tube. While thismechanism avoids some of the deficiencies associated with a closuremechanism which has a ramped camming surface on the anvil, it stillrequires relative movement between the closure tube and the anvil.Consequently, not all of the anvil may be used for staple formation. Thegreater anvil length may create flexing or twisting when thick tissue isclamped, potentially resulting in staple malformation. The gap betweenthe tissue-contacting surfaces when the anvil is in the open position isstill less than desirable.

Therefore, in view of the deficiencies inherent in those clampingmechanisms for endoscopic surgical instruments which have beenpreviously described, an endoscopic surgical instrument with a betterclamping or grasping mechanism is desired. This clamping mechanism wouldcause relative movement of the jaws of the end effector of theinstrument from an open position where tissue can be placed between thejaws to a closed position for clamping or grasping of that tissue. Themechanism would reduce frictional losses and therefore provide greaterefficiency than those mechanisms which have been described in theliterature or elsewhere. It would also take full advantage of the entirelength of the upper jaw, which frequently represents the anvil, andconsequently reduce flexing or twisting of the jaws when tissue isclamped. Additionally, an efficient clamping mechanism which enables thecreation of a wider gap between the jaws in the open position wouldfacilitate the positioning of tissue in the jaws as well as cartridgeremoval and reloading. Furthermore, it would be desirable if such aclamping mechanism could be developed which provides for a positiveopening between the jaws in their open position so that the jaws can beused as forceps or graspers.

SUMMARY OF THE INVENTION

The invention is a surgical instrument which comprises six basicelements. These elements are the following: a) a rigid frame forgripping the instrument, b) an elongated shaft extending from the frameand having a distal end, c) an end effector extending from the shaftdistal end which includes first and second jaws each having proximal anddistal ends, d) a first post cooperatively engaged with the proximal endof the second jaw, e) a pusher member affixed to the proximal end of thesecond jaw, and f) an actuator at least partially housed in the frame.

The jaws of the end effector are moveable relative to each other from anopen position for receiving bodily tissue between them to a closedposition for clamping or grasping this tissue. The first jaw includes anelongated channel having a base and first and second sidewalls. Each ofthe sidewalls has proximal and distal ends, and the sidewalls extendfrom the base toward the second jaw. Each sidewall has a mutuallyopposed elongated slot. Each of the slots is displayed diagonallyupwards from a lowermost end adjacent the proximal end of the sidewallto an uppermost end toward the distal end of the sidewall. In addition,the second jaw includes a tissue-contacting surface.

The first post which is cooperatively engaged with the second jaw isreceived within the mutually opposed elongated slots where it can slidewithin the slots.

The pusher member which is affixed to the second jaw is disposedadjacent the tissue-contacting surface of the second jaw. In certainembodiments, the distal end of the elongated shaft may act as the pushermember. The pusher member is moveable from a rearward position to aforward position. When the pusher member is in the rearward position,the first pin is positioned at the lowermost ends of the slots and thedistal end of the second jaw is displayed rearward of the distal end ofthe first jaw. When the post and the second jaw are positioned in thismanner, the first and second jaws are displayed in their open position.When the pusher member is in the forward position, the first post hastraveled to the uppermost ends of the slots and the distal end of thesecond jaw is adjacent to the distal end of the first jaw. In thisposition, the first and second jaws are displayed in their closedposition.

The actuator is operatively connected to the pusher member incooperation with the elongated shaft. It effects movement of the pushermember from the forward position to the rearward position. Consequently,the first and second jaws are moved from their opened to closedpositions.

The surgical instrument of this invention includes a mechanism to moreefficiently clamp or grasp tissue between the jaws of an end effector.The pusher member does not move relative to the second jaw to move thesecond jaw from a position spaced apart from the first jaw to a positionadjacent the first jaw. Rather, the pusher member is affixed to theproximal end of the second jaw, so that when the pusher member movesrearwardly, the second jaw moves rearwardly in tandem. Similarly, whenthe pusher member moves forwardly, the second jaw moves forwardly withit. Fundamentally, the open and closed positions of the first and secondjaws are created by the movement of the first post as it rides in theslot of the first sidewall from the lowermost end adjacent the proximalend of the sidewall to the uppermost end toward the sidewall distal end.

Significantly, the damping or gasping mechanism does not use theconventional ramped camming surface to move the second jaw from its opento closed positions. Accordingly, the second jaw does not require aramped camming surface at its proximal end, and it is unnecessary forthe pusher member to move forwardly relative to the second jaw toprovide a camming force on this jaw to effect closure. Therefore, theinefficiencies inherent in producing the frictional forces necessary tocam the second jaw toward its closed position have been eliminated.Ultimately, since the frictional forces have been reduced, the clampingmechanism in the surgical instrument of this invention requires the userto generate less force to clamp tissue between the jaws in comparison tothe force required for the conventional camming mechanism.

The elimination of the conventional camming mechanism for clampingprovides another significant benefit. Since the camming surface on thesecond jaw has been removed, substantially the entire length of thesecond jaw may be used to clamp the tissue. In fact, the pusher memberwhich moves the jaws from their open to closed positions is positionedadjacent the tissue-contacting surface of the second jaw. Theoperational length of the second jaw is consequently substantially thesame as the actual length of the jaw. The second jaw can therefore befabricated from a thinner beam to reduce the weight of the instrument,and the tendency of the jaws to flex or twist when tissue is clampedbetween them is reduced.

Another additional benefit to the clamping mechanism of the surgicalinstrument of this invention is the ability to more convenientlyposition tissue between the jaws when the jaws are in their openposition. This is so because the second jaw is positioned rearwardly ofthe distal end of the first jaw when the jaws are in their openposition. This rearward positioning of the second jaw creates a widergap between the jaws in the open position, and therefore enhances theability of the user of the instrument to position the tissue between thejaws. When the first jaw includes a staple cartridge received in theelongated channel of the first jaw, it also enhances the user's abilityto remove a spent cartridge from the channel and reload it with a newone.

Finally, since the pusher member is affixed to the proximal end of thesecond jaw, the second jaw will remain in its open position until theactuator is manipulated to effect movement of the pusher member. Incontrast, the camming mechanism of the prior art typically relied on aspring bias to maintain the second jaw in its spaced apart position. Assuch, it could easily be moved to a closed position adjacent the firstjaw when the user did not want it to be moved to this position. In otherwords, the clamping or grasping mechanism incorporated into the surgicalinstrument of this invention provides a secure opening, and thereforeprovides greater reliability when the jaws are being positioned tomanipulate tissue in varied ways during the surgical procedure.

The surgical instrument of this invention derives its greatest benefitand is primarily adapted for endoscopic surgical procedures. However, itis entirely foreseeable and within the scope of this invention to findapplications for the surgical instrument for this invention in not onlyendoscopic surgical procedures, but also conventional open surgicalprocedures as well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the most preferred surgical instrumentof the invention, which is an endoscopic linear cutter.

FIG. 2 is an exploded perspective view of the end effector of the linearcutter.

FIG. 3 is an assembled perspective view of the end effector of thelinear cutter.

FIG. 4 is an assembled perspective view of the end effector includingthe pusher member in its rearward position and the jaws in their openposition for receiving bodily tissue therebetween.

FIG. 5 is an assembled perspective view of the end effector includingthe pusher member in its forward position and the jaws in their closedposition for clamping the bodily tissue.

FIG. 6 is a side elevation of the endoscopic linear cutter with the tophalf of the molded frame and the top half of the actuator for the pushermember removed. The instrument is shown with the jaws in their openposition. The distal end has been foreshortened for clarity.

FIG. 7 is a side elevation of the endoscopic linear cutter with the tophalf of the molded frame and the top half of the actuator for the pushermember removed. The instrument is shown with its clamping triggercompressed and its firing trigger in its firing position. Accordingly,the instrument is shown with the jaws in their closed position. Thedistal end has been foreshortened for clarity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, there is shown a general illustration ofan endoscopic linear cutter 10 which is the preferred surgicalinstrument of this invention. The cutter has a rigid frame 11 forgripping the instrument, an elongated shaft 12 in the form of acylindrical tube extending from the frame, and an end effector 13attached to the distal end 14 of the shaft. The frame has an actuator 15which is operatively connected to the end effector for activating theclamping and firing mechanisms of the end effector. The actuatorincludes a palm grip handle 16, a clamping trigger 17 and a firingtrigger 18. The end effector includes a first jaw 19 having proximal anddistal ends 20 and 21, respectively. Similarly, the end effectorincludes a second jaw 22 having proximal and distal ends 23 and 24,respectively. The first jaw is shaped in the form of an elongatedchannel for receiving a staple cartridge 25 (slots for staples notshown). The staple cartridge has a longitudinal slot 26 for the passageof a knife blade (not shown) to cut the fastened tissue between rows offormed staples. The second jaw represents an anvil against which thestaples are formed. When the clamping trigger is squeezed against thepalm grip handle, tissue which is positioned between the cartridge andanvil is clamped. Once the tissue is clamped, the firing trigger canthen be squeezed against the clamping trigger to fire staples from thecartridge and through the tissue for formation of the staples againstthe anvil. To facilitate the use of the cutter in an endoscopic surgicalprocedure, the elongated shaft 12 is an elongated cylindrical tube whichcan be fitted through a trocar cannula. Endoscopic linear cutters arewell known, and the details of particular clamping and firing mechanismsare described in numerous patents. For example, see U.S. Pat. Nos.5,040,715 and 5,307,976.

Referring to FIGS. 2 and 3, the details of the end effector 13 areillustrated. The primary components of the end effector are theelongated channel 19 which represents the first jaw, the anvil 22 whichrepresents the second jaw, the first slot post 27 attached to theproximal end 23 of the, anvil for cooperative sliding movement within apair of anvil guide slots 28 and 29, respectively, and the cylindricaltube 12, which in this particularly preferred embodiment acts as thepusher member for moving the anvil relative to the channel from its opento closed positions. For simplicity and clarity, the staple cartridge 25shown in FIG. 1 which fits into the elongated channel is not shown.

The elongated channel 19 has a base 30 and first and second sidewalls 31and 32, respectively. The first sidewall has proximal and distal ends 33and 34, respectively. Likewise, the second sidewall has proximal anddistal ends 35 and 36, respectively. The sidewalls oppose each other andextend from the base in a generally parallel relationship toward theanvil. A staple cartridge can be inserted into the channel so that thebottom of the cartridge sits on the base and the sides of the cartridgefit snugly against the interior walls of the sidewalls of the channel.First and second cartridge clips 37 and 38, respectively, at the distalend of the sidewalls insure a tight fit of the cartridge when it issnapped into the channel. The first and second elongated, anvil guideslots 28 and 29 are displayed on the first and second sidewalls,respectively. Each sidewall extends diagonally upward from a lowermostend adjacent the proximal end 33 of the sidewall to an uppermost endwhich is positioned distally of the lowermost end. Adjacent the proximalend of each sidewall, there are first and second retainer slots 39 and40, respectively, and first and second retainer clips 41 and 42,respectively.

The anvil has a tissue contacting surface 43 which faces the elongatedchannel. Adjacent the proximal end of the tissue-contacting surface,there are two posts which are attached to the anvil. The first post 27is a long slot post attached at the proximal most position on the anviland received in the first and second anvil guide slots of the channel.The second post 44 is a shorter slide post positioned distally of thefirst post. The second post rests on first and second slide surfaces 45and 46, respectively, of the sidewalls of the channel when tissue is notpresent between the jaws. On the surface of the anvil opposite that ofthe tissue-contacting surface, there is a closure tube bearing surface47 and a chamfer ramp 48.

The distal end 13 of the closure tube 12 cooperates with the anvil tomove the anvil from open to closed positions relative to the elongatedchannel. Accordingly, it has an anvil thrust surface 49 in contact withthe closure tube bearing surface 47 of the anvil, and a chamferedsurface embedded on the interior of the distal end of the closure tube(not shown) which likewise cooperates with the chamfer ramp of theanvil. There are first and second securement slots 50 and 51,respectively, displayed on the distal end of the closure tube which areused to secure the tube to the anvil. The manner in which the securementslots are used to secure the tube to the anvil is illustrated anddescribed in more detail in connection with the discussion of FIGS. 4and 5 below.

The elongated channel 19 is affixed to the distal end of the shaft ofthe instrument to a retainer rod 52. The retainer rod is housed withinthe elongated shaft, or in other words, it is fitted within the hollowinterior of the cylindrical tube which functions as the pusher member.The retainer rod has a channel retainer 53 at its distal end. Thechannel retainer consists of first and second solid, arcuate surfaces 54and 55, respectively, extending radially outwardly from first and secondretainer walls 56 and 57, respectively. The channel retainer alsoincludes a first indent portion 58 and a second indent portion (notshown) disposed within the first and second retainer walls,respectively. The channel retainer is fitted into the first and secondretainer slots 39 and 40 at the proximal end of the elongated channel,and the first and second retainer clips 41 and 42 are biased against thefirst and second indents on the retainer walls. In this manner, thedistal end of the retainer rod is attached to the proximal end of theelongated channel. Finally, at the proximal end of the retainer rod(FIG. 3), there is a rod retention groove 59. This groove facilitatesthe attachment of the proximal end of the rod within the frame 11 of theinstrument to prevent axial movement of the rod while simultaneouslypermitting rotational movement.

FIGS. 4 and 5 illustrate the positional relationship between theelongated channel 19 and anvil 22 in the open and closed positions.First, it should be emphasized that there is substantially no relativemovement between the closure tube and the anvil when the jaws are movedfrom the open to closed positions. In other words, as the closure tubemoves forwardly, the anvil moves forwardly in tandem. Likewise, as theclosure tube moves rearwardly, the anvil moves rearwardly as well. Ananvil retainer detent 60 is created to affix the distal end 14 of theclosure tube to the anvil when that portion of the closure tubepositioned between the first and second securement slots 50 and 51 (FIG.2) is crimped.

Referring now specifically to FIG. 4, the closure tube is shown in itsrearward position. In this position, the first slot post is positionedwithin the lowermost end of the anvil guide slots on the sidewalls ofthe channel and the jaws are in their open position. In the openposition, the anvil is spaced apart from the elongated channel, and thedistal end 24 of the anvil is rearward of the distal end 21 of thechannel. Turning to FIG. 5, when the closure tube is moved forwardly toits forward position, the jaws are in their closed position. The firstslot post rides in the anvil guide slots from the lowermost end to theuppermost end on the sidewalls, and the second slide post slides on thefirst and second slide surfaces 45 and 46 of the channel in a distaldirection during opening of the jaws when tissue is not present. Whenthe jaws are in the closed position, the anvil is adjacent to thechannel. When tissue is present, the second slide post may be lifted offthe slide surfaces 45 and 46 of the channel, due to the resistance ofthe tissue to clamping. In addition, since the closure tube and anvilhave moved forwardly in tandem, the distal end of the anvil is no longerrearward of the distal end of the channel, but rather the distal ends ofthe anvil and channel are substantially coincident with each other.

Referring to FIGS. 6 and 7, there is shown the clamping sequence to movethe jaws from an open position for inserting bodily tissue between thejaws, to a closed position for clamping the tissue. When the clampingtrigger 17 of the actuator 15 is squeezed against the palm grip handle16, the closure tube 12 is caused to move from its rearward position toits forward position to consequently move the anvil from a positionspaced from the cartridge-filled channel to a position adjacent thechannel. In FIGS. 6 and 7, the bottom half of the frame is illustrated.The top half of the frame can be simply molded to the bottom half tocompletely enclose the mechanisms for clamping and firing. When theclamping trigger 17 is squeezed, it pivots about a bearing pin 61. Aclosure pinion 62 cooperates with an actuator rack 63, and the actuatorrack moves longitudinally forward. The actuator rack is a component of aclosure tube actuator 64. The closure tube actuator has at its distalend first and second arms 65 and 66, respectively, which are affixed tothe proximal end 67 of the closure tube. Consequently, as the clampingtrigger is squeezed and the actuator rack moves forwardly, the closuretube actuator likewise moves forwardly to move the closure tube from itsrearward to forward positions. The retention rod 52 is fixed to theframe because the rod retention groove 59 comes into contact with firstand second mating bosses on the bottom and top halves of the frame (notshown). This particular configuration enables the retention rod toremain in an axially fixed position, yet allows the user to rotate theretention rod, closure tube and end effector by rotating a rotation knob68. Once the clamping trigger has been squeezed to clamp tissue betweenthe jaws, the firing trigger can subsequently be squeezed to firestaples into the tissue while simultaneously cutting between rows ofstaples. Further details of the mechanism for clamping the tissuebetween the jaws, and the structure and mechanisms for firing andcutting the tissue are described in U.S. Pat. No. 5,465,895.

Although this invention has been described in connection with its mostpreferred embodiment, the reader should not use this description tolimit the scope of the claimed invention, which is set forth inconnection with the claims appearing below. Obviously, numerousadditional embodiments would be readily apparent to those skilled inthis art, and would fall within the scope and spirit of the claimedinvention. For example, it is contemplated that while the invention isparticularly adapted for endoscopic applications, it is entirelypossible that numerous applications for this invention in open surgerycan be found. In addition, although the end effector has been describedin connection with an endoscopic linear cutter, it is readily apparentthat a myriad of end effector configurations can be used which fallwithin the scope of the claims which follow.

What is claimed is:
 1. A surgical instrument comprising:a) a rigid framefor gripping said instrument; b) an elongated shaft extending from saidframe and having a distal end; c) an end effector extending from saidshaft distal end, said end effector including first and second jaws eachhaving proximal and distal ends, said jaws movable relative to eachother from an open position for receiving bodily tissue therebetween toa closed position for clamping or grasping said tissue, said first jawincluding an elongated channel having a base and first and secondsidewalls each having proximal and distal ends, said sidewalls extendingfrom said base toward said second jaw, each of said sidewalls having amutually opposed elongated slot, each of said slots disposed diagonallyupwards from a lowermost end adjacent said proximal end of said sidewallto an uppermost end toward said distal end of said sidewall, said secondjaw including a tissue-contacting surface; d) a first post cooperativelyengaged with said proximal end of said second jaw, said first post beingreceived within said mutually opposed elongated slots for slidingmovement therein; e) a pusher member at said proximal end of said secondjaw and adjacent said tissue-contacting surface, said pusher memberbeing movable from a rearward position to a forward position, whereinwhen said pusher member is in said rearward position, said first post ispositioned at said lowermost ends of said slots and said distal end ofsaid second jaw is rearward of said distal end of said first jaw so asto position said jaws in said open position, and a mechanism foraffixing the pusher member and said second jaw so that when said pushermember is moved forwardly from said rearward position to said forwardposition, said second jaw is moved forwardly in tandem with said pushermember, said first post has traveled to said uppermost ends of saidslots, and said distal end of said second jaw is positioned adjacent tosaid distal end of said first jaw so as to position said jaws in saidclosed position; and f) an actuator at least partially housed in saidframe and operatively connected to said pusher member in cooperationwith said elongated shaft to effect movement of said pusher member fromsaid forward to said forward positions so as to move said jaws from saidopen to said closed positions.
 2. The surgical instrument of claim 1wherein each of said first and second sidewalls has a slide surface, andsaid instrument further comprises a second post attached to said secondjaw distally of said first post, wherein when said pusher member ismoved from said rearward position to said forward position, said secondpost slides on each of said slide surfaces of said sidewalls when saidbodily tissue is not received between said jaws.
 3. The surgicalinstrument of claim 2 wherein said elongated shaft has a longitudinalaxis, and said first and second posts are attached to said second jawsubstantially perpendicular to said longitudinal axis.
 4. The surgicalinstrument of claim 1 wherein said elongated shaft is a cylindricaltube.
 5. The instrument of claim 4 wherein said distal end of saidcylindrical tube is integral with said pusher member.
 6. The instrumentof claim 1 wherein said instrument is an endoscopic surgical instrument.7. The instrument of claim 1 wherein a staple cartridge is receivedwithin said elongated channel of said first jaw between said first andsecond sidewalls.
 8. The instrument of claim 7 wherein said second jawincludes an anvil for forming staples thereon.
 9. The instrument ofclaim 8 wherein said pusher member has a distal end and said anvil has aproximal end, and said anvil proximal end has a bearing surface and achamfer ramp, said surface and ramp abutting said distal end of saidpusher member.
 10. The instrument of claim 1 wherein said actuatorincludes a pistol grip handle, a clamping trigger, and a firing trigger.11. A surgical instrument comprising:a) a rigid frame for gripping saidinstrument; b) a cylindrical closing tube extending from said frame andhaving a distal end; c) an end effector extending from said distal end,said end effector including first and second jaws each having proximaland distal ends, said jaws movable relative to each other from an openposition for receiving bodily tissue therebetween to a closed positionfor clamping or grasping said tissue, said first jaw including anelongated channel having a base and first and second sidewalls eachhaving proximal and distal ends, said sidewalls extending from said basetoward said second jaw, each of said sidewalls having a mutually opposedelongated slot, each of said slots disposed diagonally upwards from alowermost end adjacent said proximal end of said sidewall to anuppermost end toward said distal end of said sidewall, said proximal endof said second jaw affixed to said tube distal end; d) a first postcooperatively engaged with said proximal end of said second jaw, saidfirst post being received within said mutually opposed elongated slotsfor sliding movement therein; and e) an actuator at least partiallyhoused in said frame and operatively connected to said closure tube toeffect movement of said closure tube from a rearward position to aforward position so as to move said jaws from said open to said closedpositions and; f) a mechanism affixing said closure tube to said secondjaw so that forward and rearward movement of said closure tube and saidsecond jaw occurs in tandem relative to each other, wherein when saidclosure tube is in said rearward position, said first post is positionedat said lowermost ends of said slots and said distal end of said secondjaw is rearward of said distal end of said first jaw so as to positionsaid jaws in said open position, and when said closure tube is movedforwardly from said rearward position to said forward position, saidsecond jaw is moved forwardly in tandem with said closure tube, saidfirst post has traveled to said uppermost ends of said slots, and saiddistal end of said second jaw is positioned adjacent to said distal endof said first jaw so as to position said jaws in said closed positions.12. The surgical instrument of claim 11 wherein each of said first andsecond sidewalls has a slide surface, and said instrument furthercomprises a second post attached to said second jaw distally of saidfirst post, wherein when said closure tube is moved from said rearwardposition to said forward position, said second post slides on each ofsaid slide surfaces of said sidewalls.
 13. The surgical instrument ofclaim 12 wherein said closure tube has a longitudinal axis, and saidfirst and second posts are attached to said second jaw substantiallyperpendicular to said longitudinal axis.
 14. The instrument of claim 11wherein said instrument is an endoscopic surgical instrument.
 15. Theinstrument of claim 11 wherein a staple cartridge is received withinsaid elongated channel of said first jaw between first and secondsidewalls.
 16. The instrument of claim 15 wherein said second jawincludes an anvil for forming staples thereon.
 17. The instrument ofclaim 16 wherein said anvil has a proximal end including a bearingsurface and a chamfer ramp, and said tube distal end abuts said surfaceand ramp.
 18. The instrument of claim 11 wherein said actuator includesa pistol grip handle, a clamping trigger, and a firing trigger.